It shows the feelings and the mood and setting of the paintings. Hope this helps!
Music a global phenomenon. People around the world appreciates music even though they don't understand the lyrics (because of the language). Music is a universal language. It makes people unite. For example, the recent famous song from Disney called "Let it Go". People around the world made different translations just to sing that song. I also agree to what sanaybrown posted, it's a way people express their feelings.
